This review gives a worldwide overview on Power-to-Gas projects producing hydrogen or renewable substitute natural gas focusing projects in central Europe. It deepens and completes the content of ...previous reviews by including hitherto unreviewed projects and by combining project names with details such as plant location. It is based on data from 153 completed, recent and planned projects since 1988 which were evaluated with regards to plant allocation, installed power development, plant size, shares and amounts of hydrogen or substitute natural gas producing examinations and product utilization phases. Cost development for electrolysis and carbon dioxide methanation was analyzed and a projection until 2030 is given with an outlook to 2050.
The results show substantial cost reductions for electrolysis as well as for methanation during the recent years and a further price decline to less than 500 euro per kilowatt electric power input for both technologies until 2050 is estimated if cost projection follows the current trend. Most of the projects examined are located in Germany, Denmark, the United States of America and Canada. Following an exponential global trend to increase installed power, today's Power-to-Gas applications are operated at about 39 megawatt. Hydrogen and substitute natural gas were investigated on equal terms concerning the number of projects.
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•Electrolysis and methanation costs are estimated to fall by up to 75% under 500 €/kWel until 2050.•Most projects are located in Germany, Denmark, the United States and Canada.•95 Power-to-Gas projects with a combined load of 38.6 MWel are active in early 2019.•Exponential global increase in installed PtG-capacity is expected between 1993 and 2050.•The years 2012–2015 mark a breakthrough in average plant size and installed capacity.
Ultra-hot Jupiters are emerging as a new class of exoplanets. Studying their chemical compositions and temperature structures will improve our understanding of their mass loss rate as well as their ...formation and evolution. We present the detection of ionized calcium in the two hottest giant exoplanets – KELT-9b and WASP-33b. By using transit datasets from CARMENES and HARPS-N observations, we achieved high-confidence-level detections of Ca II using the cross-correlation method. We further obtain the transmission spectra around the individual lines of the Ca II H&K doublet and the near-infrared triplet, and measure their line profiles. The Ca II H&K lines have an average line depth of 2.02 ± 0.17% (effective radius of 1.56 Rp) for WASP-33b and an average line depth of 0.78 ± 0.04% (effective radius of 1.47 Rp) for KELT-9b, which indicates that the absorptions are from very high upper-atmosphere layers close to the planetary Roche lobes. The observed Ca II lines are significantly deeper than the predicted values from the hydrostatic models. Such a discrepancy is probably a result of hydrodynamic outflow that transports a significant amount of Ca II into the upper atmosphere. The prominent Ca II detection with the lack of significant Ca I detection implies that calcium is mostly ionized in the upper atmospheres of the two planets.
We report on the detailed analysis of a gravitationally lensed Y-band dropout, A2744_YD4, selected from deep Hubble Space Telescope imaging in the Frontier Field cluster Abell 2744. Band 7 ...observations with the Atacama Large Millimeter/submillimeter Array (ALMA) indicate the proximate detection of a significant 1 mm continuum flux suggesting the presence of dust for a star-forming galaxy with a photometric redshift of . Deep X-SHOOTER spectra confirms the high-redshift identity of A2744_YD4 via the detection of Ly emission at a redshift z = 8.38. The association with the ALMA detection is confirmed by the presence of O iii 88 m emission at the same redshift. Although both emission features are only significant at the 4 level, we argue their joint detection and the positional coincidence with a high-redshift dropout in the Hubble Space Telescope images confirms the physical association. Analysis of the available photometric data and the modest gravitational magnification ( ) indicates A2744_YD4 has a stellar mass of ∼2 × 109 , a star formation rate of ∼20 yr−1 and a dust mass of ∼6 × 106 . We discuss the implications of the formation of such a dust mass only after the onset of cosmic reionization.
Ecological interactions between different species of yeasts have been observed and described extensively, but the mechanisms of interaction remain poorly understood. A hindrance to the ...characterization of multispecies yeast ecosystems is the lack of accurate methods for rapid real-time analysis of population dynamics in synthetic multispecies consortia. Here, we sought to accelerate and improve the sensitivity of ecological modelling and characterization of a synthetic yeast ecosystem by developing a flow cytometry–based method that tracks and sorts fluorescently tagged individual yeast species in real time during growth in model multispecies consortia. A protocol for integrative genetic modification of non-conventional yeasts was developed. The application of the method was demonstrated in a model four-species synthetic wine-yeast ecosystem that consisted of species commonly isolated from natural wine fermentations. The data show that this method allows for rapid generation of meaningful ecological data that contributes to our understanding of multispecies synthetic yeast ecosystems. Furthermore, interspecies interactions have been shown to impact the evolution of yeasts in natural ecosystems, and this platform will provide an ideal tool to better evaluate the impact of biotic selection pressures.
Key Points
• Fluorescent labelling of yeast species in a consortium for multicolour flow cytometry
• Method developed to track population dynamics of multispecies yeast consortia
• Enables real-time visualization, manipulation and response analyses of population dynamics
• Produces accurate, reproducible data with powerful visual analyses potential at a rapid rate
We present the first results from the KMOS (K-band Multi-Object Spectrograph) AGN (active galactic nuclei) Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic (IFS) survey of z ≳ ...0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN (L
2–10 keV = 1042–1045 erg s−1), for which we observed O iii (z ≈ 1.1–1.7) or Hα emission (z ≈ 0.6–1.1). The targets have X-ray luminosities representative of the parent AGN population and we explore the emission-line luminosities as a function of X-ray luminosity. For the O iii targets, ≈50 per cent have ionized gas velocities indicative of gas that is dominated by outflows and/or highly turbulent material (i.e. overall line widths ≳600 km s−1). The most luminous half (i.e. L
X > 6 × 1043 erg s−1) have a ≳2 times higher incidence of such velocities. On the basis of our results, we find no evidence that X-ray obscured AGN are more likely to host extreme kinematics than unobscured AGN. Our KASHz sample has a distribution of gas velocities that is consistent with a luminosity-matched sample of z < 0.4 AGN. This implies little evolution in the prevalence of ionized outflows, for a fixed AGN luminosity, despite an order-of-magnitude decrease in average star formation rates over this redshift range. Furthermore, we compare our Hα targets to a redshift-matched sample of star-forming galaxies and despite a similar distribution of Hα luminosities and likely star formation rates, we find extreme ionized gas velocities are up to ≈10 times more prevalent in the AGN-host galaxies. Our results reveal a high prevalence of extreme ionized gas velocities in high-luminosity X-ray AGN and imply that the most powerful ionized outflows in high-redshift galaxies are driven by AGN activity.
ABSTRACT The scatter in the relationship between the strength of C ii 158 $\mu$m emission and the star formation rate at high redshift has been the source of much recent interest. Although the ...relationship is well established locally, several intensely star-forming galaxies have been found whose C ii 158 $\mu$m emission is either weak, absent, or spatially offset from the young stars. Here we present new ALMA data for the two most distant gravitationally lensed and spectroscopically confirmed galaxies, A2744_YD4 at z = 8.38 and MACS1149_JD1 at z = 9.11, both of which reveal intense O iii 88 $\mu$m emission. In both cases we provide stringent upper limits on the presence of C ii 158 $\mu$m with respect to O iii 88 $\mu$m. We review possible explanations for this apparent redshift-dependent C ii deficit in the context of our recent hydrodynamical simulations. Our results highlight the importance of using several emission line diagnostics with ALMA to investigate the nature of the interstellar medium in early galaxies.
Abstract
Mergers of galaxies are thought to cause significant gas inflows to the inner parsecs, which can activate rapid accretion on to supermassive black holes (SMBHs), giving rise to active ...galactic nuclei (AGN). During a significant fraction of this process, SMBHs are predicted to be enshrouded by gas and dust. Studying 52 galactic nuclei in infrared-selected local luminous and ultraluminous infrared galaxies in different merger stages in the hard X-ray band, where radiation is less affected by absorption, we find that the amount of material around SMBHs increases during the last phases of the merger. We find that the fraction of Compton-thick (CT, N H ≥ 1024 cm− 2) AGN in late-merger galaxies is higher ($f_{\rm \,CT}=65^{+12}_{-13}{\rm per\, cent}$) than in local hard X-ray selected AGN (f CT = 27 ± 4 per cent), and that obscuration reaches its maximum when the nuclei of the two merging galaxies are at a projected distance of D12 ≃ 0.4–10.8 kpc ($f_{\rm \,CT}=77_{-17}^{+13}{\rm per\, cent}$). We also find that all AGN of our sample in late-merger galaxies have N H > 1023 cm− 2, which implies that the obscuring material covers $95^{+4}_{-8}{\rm per\, cent}$ of the X-ray source. These observations show that the material is most effectively funnelled from the galactic scale to the inner tens of parsecs during the late stages of galaxy mergers, and that the close environment of SMBHs in advanced mergers is richer in gas and dust with respect to that of SMBHs in isolated galaxies, and cannot be explained by the classical AGN unification model in which the torus is responsible for the obscuration.
Enhanced emission from the dense gas tracer HCN (relative to HCO+) has been proposed as a signature of active galactic nuclei (AGN). In a previous single-dish millimeter line survey we identified ...galaxies with HCN/HCO+ (1-0) intensity ratios consistent with those of many AGN but whose mid-infrared spectral diagnostics are consistent with little to no ( 15%) contribution of an AGN to the bolometric luminosity. To search for putative heavily obscured AGN, we present and analyze NuSTAR hard X-ray (3-79 keV) observations of four such galaxies from the Great Observatories All-sky LIRG Survey. We find no X-ray evidence for AGN in three of the systems and place strong upper limits on the energetic contribution of any heavily obscured ( ) AGN to their bolometric luminosity. The upper limits on the X-ray flux are presently an order of magnitude below what XDR-driven chemistry models predict are necessary to drive HCN enhancements. In a fourth system we find a hard X-ray excess consistent with the presence of an AGN, but contributing only ∼3% of the bolometric luminosity. It is also unclear if the AGN is spatially associated with the HCN enhancement. We further explore the relationship between HCN/HCO+ (for several Jupper levels) and / for a larger sample of systems in the literature. We find no evidence for correlations between the line ratios and the AGN fraction derived from X-rays, indicating that HCN/HCO+ intensity ratios are not driven by the energetic dominance of AGN, nor are they reliable indicators of ongoing supermassive black hole accretion.
The aim of our review is to identify the key job resources and demands of nursing staff by integrating findings from previously published reviews along the lines of the JD-R model. Understanding ...these is highly relevant given the ever-increasing pressure in nursing work and the challenges of healthcare organizations in recruiting qualified staff. It is also an important step toward developing targeted workplace interventions. A comprehensive search of the literature identified 14 quantitative and qualitative reviews that were included in our integrative review of reviews. Thematic analysis identified three key job demands and six key job resources of nursing staff, namely work overload, lack of formal rewards, work-life interference, supervisor support, fair and authentic management, transformational leadership, interpersonal relations, autonomy and professional resources. Our results corroborate findings from previous reviews, expand the relevance and generalizability by considering a broader range of relevant health-related and motivational outcomes, and highlight the importance of leadership practices in nursing.
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![The absence of [C ii ] 158 ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1745-3925_0035-8711/small "The absence of [C ii ] 158 $\mu$m emission in spectroscopically confirmed galaxies at z > 8")
